Method for automatically stopping and restarting an engine powered generator

ABSTRACT

A method and apparatus for restarting a generator set following a nuisance shutdown.

CROSS REFERENCES TO CO-PENDING APPLICATIONS

This application is related to co-pending U.S. application Ser. No.08/979,903, filed on date even herewith, entitled "AUTOMATIC PRETRIP FORENGINE POWERED GENERATOR".

BACKGROUND OF THE INVENTION

The present invention pertains generally to the field of generator sets.In particular, the present invention pertains to engine controls forgenerator sets used to power heating and cooling devices used to controlthe temperature of cargo containers.

Containerized shipment of goods has become a widely accepted means oftransporting cargo around the world. Modern containers can be stacked onthe decks of ships for shipment overseas. When a container ship arrivesat a port, the containers can be efficiently removed from the ship bycrane. At the port, the containers can be stacked for further shipmentby truck or rail. When the containers are shipped by truck, a singlecontainer is usually placed on a semi-trailer chassis. Each rail cargenerally can support up to four containers.

When the cargo in the container is comprised of perishables such as foodstuffs or flowers, the temperature in each of the containers must becontrolled to prevent loss of the cargo during shipment. For shipmentsof perishable goods, specialized containers have been developed whichinclude temperature control units for refrigeration and/or heating.While on board ship, the containers can be connected to a ship'sgenerator to provide power to the temperature control units. When thecontainers are in port, they may be connected to a power source providedby a local utility.

When, however, the containers are in transit by railcar or truck,generator sets must be provided to power the temperature control units.Such generator sets usually include a diesel engine to power a generatorwhich in turn provides electric power to the temperature control units.Such generator sets can be clipped directly to a container or fastenedto a trailer chassis.

During shipment, the temperature control units and generator sets mustoperate for extended periods of time. For example, when lettuce isshipped from California to the northeastern United States, the sets mayrun periodically for several days. During this extended period of time,the temperature control unit and generator set will operate for extendedperiods of time without inspection by transportation workers. This isparticularly true in the case of rail transportation where scores ofrailcars may, for extended periods of time, be in transport whileaccompanied by only two or three transportation workers.

During these extended periods of time when the control units andgenerator sets are substantially unmonitored by transportation workersand may experience a "nuisance" shutdown, causing a loss of power to thetemperature control unit. This may result in a loss of the perishablecargo. This is particularly true if ambient temperature conditions arevery hot or very cold. A nuisance shutdown is usually caused by atransitive condition which may exist briefly, but does not involve achronic generator set problem which will persist when the transitivecondition abates. Thus, the engine or generator set could be restartedif an operator notices that the shutdown had occurred.

Thus, providing a consistent source of power to the containertemperature control units is essential if the loss of perishable cargois to be prevented. A number of methods and apparatus have been proposedfor controlling generators. None of the these, however, have addressedthe serious problem of correcting generator set nuisance shutdownsduring an extended period where the generator set is unattended.

U.S. Pat. No. 5,390,068 to Schultz et al. discloses a microprocessorbased generator set controller apparatus and method which monitorsvarious engine and generator faults and uses the generated signals tocontrol the operation and output of the engine generator system. Schultzet al. also disclose that the controller includes self diagnostic andserial communications ports.

U.S. Pat. No. 5,561,330 to Crook discloses an automatic electric powergenerator control that automatically starts the generator engine and thegenerator when a demand is made for electric power. U.S. Pat. No.4,853,553 to Hosie discloses a control system for controlling electricgenerating apparatus including electrically heated combustion engine.Finally, U.S. Pat. No. 4,463,305 to Wineland et al. discloses a methodand system for delaying mechanical loading of an internal combustionengine by an alternator during startup of the engine by inhibiting thefield winding current of the alternator until the engine reaches apredetermined operational condition.

Thus, what has not heretofore been provided is a method and apparatusfor restarting an unattended, nuisance shutdown generator set. Such anapparatus would provide substantial advantages in the field of containershipment and particularly in the container shipment of perishable items.

The foregoing illustrates limitations known to exist in present devicesand methods. Thus, it is apparent that it would be advantageous toprovide an alternative directed to overcoming one or more of thelimitations set forth above. Accordingly, a suitable alternative isprovided including features more fully disclosed hereinafter.

SUMMARY OF THE INVENTION

The present invention relates generally to a method and apparatus forrestarting a generator set following a "nuisance" shutdown. A nuisanceshutdown may occur when the generator set experiences a transitory,environmental or operational change. Such a transitory change couldoccur as a generator set operating on a railcar passes through a lowoxygen environment such as a tunnel. In such a low oxygen environment, agenerator set powered by a diesel engine may shutdown as the dieselengine receives insufficient oxygen for diesel fuel combustion.

Whatever the cause of the nuisance shutdown, however, the assumption isthat the condition causing the nuisance shutdown is transitive, thusadversely effecting the generator set for a limited period of time.Consequently, the generator set should be operable after the transitivecondition has passed. Once the transitive condition has passed, theengine of the generator set should be capable of restarting withoutcausing permanent damage to the generator set.

The method in accordance with the present invention includes the step ofsensing whether a generator set engine has shut down during normaloperation. If the engine has shut down, during normal operation after apause for a period of time, the engine is restarted.

The method can also include the steps of sensing certain generator setoperating parameters, while the engine is running. If the parameter isnot in an appropriate operating range, the engine is shut down. Theparameter is then sensed again to determine if the parameter hasreturned to within the operating range. If the parameter has returned towithin the operating range, the engine will continue to run as requiredto meet power demands.

In accordance with the present invention, one or more parameters couldbe sensed. These parameters may include, among others, engine coolanttemperature, engine speed, oil pressure, battery voltage and fuelpressure.

An apparatus can be provided to perform the method. Such an apparatusincludes at least one engine operating parameter sensor. The apparatusalso includes a controller including means for determining whether theparameter sensed by the sensor is within operating range. The controllerincludes means for shutting down the engine if the parameter is outsidethe operating range. The controller also includes means for restartingthe engine after a period of time following a shutdown of the engine.The means for determining can also include means for redetermining thestatus of the parameter following restarting of the engine.

The apparatus can also include means for recording the time of an engineshutdown. The apparatus can also include additional sensors for sensingadditional engine operating parameters. These sensors can sense thoseparameters discussed above with respect to the method. The apparatus canalso record which parameters were operating outside of the operatingrange when the engine was shutdown.

The foregoing and other aspects will become apparent from the followingdetailed description of the invention when considered in conjunctionwith the accompanying drawing figure.

BRIEF DESCRIPTION OF THE DRAWING

The FIG. 1 is a block diagram of a generator set including a controllerin accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the FIG. 1, a generator set 10 in accordance with thepresent invention is shown in block drawing form. Generator set 10includes three principal components, a generator 12, engine 14 and acontroller 16. The controller is enclosed by controller enclosure withenclosure walls 62 represented in dashed font in the FIG. 1.

Engine 14 is preferably an industrial duty diesel engine such as anexclusive se 2.2 liter direct injection industrial duty diesel engine.Such an engine, as one skilled in the art would recognize, would includea cooling system, such as a water or liquid coolant system; an oillubricant system; an electrical system including a battery, alternatorand glow plug; and a fuel system including a fuel tank and fuel solenoidfor controlling the flow of fuel to the cylinders. A drive shaft 30transfers energy from the engine to the generator. An air filter (notshown) filters air channeled to the cylinders for combustion. The enginealso includes means for shutting down and restarting the engine 14. theshutting down/restarting means is identified generally at 63 in FIG. 1.The shutting down/restarting means is collectively comprised of wellknown electronically actuated components such as a fuel valve and astarter, and also may be include a fuel/engine preheating device if theengine 14 is a diesel engine. As shown in FIG. 1, means 63 is in signalreceiving relation with controller 16. When it is necessary to shut downthe engine, the controller 16 sends a signal to each of the componentscomprising the shutting down/restarting means, which thereby closes orotherwise shuts down the components and as a result, causes the engineto shut down. Conversely, when it is necessary to restart the engine, asignal is sent by the controller to the shutting down/restarting meanscomponents to open and/or actuate the components and thereby restart theengine.

Generator 12 could be, for example, a 15 KW, 18.75 KVA, 230, 460 VAC,3-phase, 60 Hz direct drive, brushless generator. Those skilled in theart would recognize that other generators could be advantageously usedand that the specifically recited generator is exemplary only. Theabove-described generator, as indicated, can be wired for 230 V and 460V ac power output, or some other power output. Power cable 18 can beused to deliver power to a temperature control unit for a cargocontainer or other application.

Controller 16 includes the standard controls for operating a generatorset as known to those skilled in the art. Controller 16, however, inaccordance with the present invention includes additional controls toperform the method of the present invention. The controller is connectedto the engine 14 and generator 12 to perform routine functions such asoperator-initiated engine startups and shutdowns. The engine 14 andgenerator 12 are electrically connected to controller 16 by connectioncables means 32 and 34 respectively. The controller is also connected tovarious engine component sensors. For example, the controller can beconnected to a water temperature sensor, engine rpm sensor, oil pressuresensor, and air flow sensor. Such sensors are represented generally as40a, 40b, 40c, and 40d in FIG. 1 and are shown in signal transmittingrelation with the controller 16.

Controller 16 includes processor logic which can be executed by amicroprocessor to make various engine operating decisions in response todetermining certain engine operating parameters based upon controlsensor readings. These control processes are discussed in more detailbelow.

Controller 16 preferably includes an operator interface including adisplay 20 which could be, for example, an LCD display. Controller 16also includes a keyboard or pad 22 for entering commands. Controller 16includes a memory unit 24, such as a Ramdon Access Memory ("RAM") whichcan maintain a log of certain engine operating parameters, their valuesand the time at which those values occurred particularly when an engineshutdown resulted. Memory unit 24 can be used to store other data aswell.

The arrangement of generator set components described above canadvantageously be used to execute the method of the present invention byone skilled in the art. If a generator set shutdown occurs, thecontroller will initiate an automatic restart. The engine will notautomatically restart if the processor determines that based upon sensorreadings, certain engine operating parameters are outside of appropriateranges. If restart does not occur, the controller can wait for a timeinterval, for example, a twenty minute interval and try restarting theengine again. If, because the operating parameter or parameterscontinued to be outside of the appropriate range(s), the controller canwait for another time interval, such as a twenty minute interval, andattempt another restart of the engine until the engine is successfullyrestarted or the battery charge is exhausted.

Engine shutdowns can be controller initiated if a generator setoperating parameter being monitored by the controller is determined bythe controller to be outside of normal operating ranges. Engineshutdowns can also occur for extraneous reasons and transitive ambientconditions not initiated by the controller, for example, if the engineis starved for oxygen.

Engine operating parameters which can trigger a shutdown include enginewater temperature, rpm's, oil pressure, battery voltage, and air flowrate. It can be appreciated by one skilled in the art that various otherengine parameters may advantageously be monitored and that this list isillustrative only.

The engine water temperature parameter can be used in the engineshutdown and restart routine in the illustrative manner that follows.For example, the engine is running, water temperature then exceeds 225°F. and remains above 220° F. for twenty-five seconds. Based upon theseoperating parameters readings, the controller shuts down the engine.When the water temperature drops to 190° F., the controller will restartthe engine. If the high engine water temperature condition re-occurs anexcessive number of times within a given period, the engine can beshutdown permanently until operator intervention is undertaken tocorrect the problem. When operator intervention does occur, the operatorcan use the user interface 20 to obtain data related to the conditionwhich caused the engine shutdown and/or the time at which the shutdowncondition occurred.

In the preceding example, restart was initiated by the controllersubsequent to a controller initiated engine shutdown. The automaticrestart sequence can also be used when the shutdown occurs forextraneous reasons such as the engine operating temporarily in a lowoxygen environment such as a tunnel or a small enclosure. In such acase, engine shutdown could be detected by the controller if enginerpm's drop to zero, for example.

Processor 16 can be configured to restart the engine after nuisanceshutdown as described above. The processor may also be configured to runa pretrip engine diagnostic and startup sequence. An operator initiatesthe sequence by way of the keypad 22. Once pretrip is initiated, thecontroller reads the non-running status of, for example, the followingcomponents: engine oil pressure, engine coolant level, engine airintake, filter switch, engine oil level, engine rpm, engine watertemperature, run relay, run relay feedback, preheat relay, preheat relayfeedback, start relay, excitor relay, battery volts, alternator outputvolts and excitor current.

It can be appreciated the appropriate sensors can be connected to thecontroller to measure the condition of these system components as wellas other components which could be of interest. In the non-runningstatus, engine oil pressure should be low, engine coolant level shouldbe high and each additional component or operating parameter will have aproper or normal state. If the processor determines that component orengine operating parameter is not in the proper state, an alarm codewill be generated, displayed on the user interface 22 and stored inmemory 24 to aid in diagnosing engine problems. Depending on the alarmcode, the pretrip sequence may be aborted. For example, if the problemcondition detected would cause serious engine damage, the startup willbe aborted. If these parameters are in the proper state, the controllerwill continue in the non-running pretrip sequence by energizing thepreheat output and then de-energize the preheat output. While preheatoutput is energized and de-energized both preheat feedback and batteryvolts will be checked for their proper state. The run relay is energizedand run relay feedback checked for proper state. Then the run relay isde-energized and again the run relay checked for its proper state.

After completing the non-running pretrip, the controller will start theengine. The engine start routine can include diagnostics for failure ofthe engine to crank or start, engine rpm's, oil pressure, preheatfeedback and run relay feedback. Once the engine is started, the runningpretrip continues. Prior to energizing the alternator, the engine oilpressure, engine coolant level, engine air intake filter switch, engineoil level, engine rpm, engine water temperature, battery volts,alternator output volts, and excitor current are checked to determinedwhether they are in the proper state. If it is determined that theseparameters are in the proper state, the alternator will be energized andthe engine allowed to continue to run. Finally, the display can indicatethe result of all previous checks and display a "PASS" or "FAIL". A"CHECK" condition can also be displayed indicating some parameters maynot be in a normal operating range, but would not affect capability ofthe generator set to provide output power.

Numerous characteristics and advantages of the invention covered by thisdocument have been set forth in the foregoing description. It will beunderstood, however, that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of parts without exceeding the scope of theinvention. The inventions's scope is, of course, defined in the languagein which the appended claims are expressed.

What is claimed is:
 1. A method for automatically reestablishing thesupply of electricity by a generator set where the generator set iscomprised of a generator driven by an engine, a controller in signaltransmitting and receiving relation with the engine, means for sensing anon-running value of a first engine operating parameter, the controllerhaving a memory, the controller being in signal receiving relation withthe means for sensing a non-running value of the first engine operatingparameter, and means for restarting the engine, the restarting meansbeing in signal receiving relation with the controller; the methodcomprising the steps of:a) pausing for a period of time after the enginehas been shut down; b) after pausing for the period of time, and whilethe engine is not running, determining if a non-operator initiatedengine shutdown has occurred by sensing the non-running value of thefirst engine operating parameter, transmitting the sensed non-runningvalue to the controller, and the controller comparing the sensednon-running value of the first engine operating parameter to apredetermined acceptable non-running value for the first engineoperating parameter stored in the controller memory; c) if thenon-running value of the first engine operating parameter is within anacceptable non-running value for the first engine parameter,automatically restarting the engine by initiating an engine restartingroutine comprising the step of sending a signal from the controller tothe engine restarting means.
 2. The method as claimed in claim 1,further comprising the steps of obtaining the value of a second engineoperating parameter after the engine has been restarted; determining ifthe second engine parameter is operating within a predeterminedacceptable operating range; and shutting down the engine if the secondengine operating parameter is not within the predetermined acceptableoperating range for the second engine operating parameter.
 3. The methodas claimed in claim 2, wherein the second engine operating parameter isengine coolant temperature.
 4. The method as claimed in claim 2, whereinthe second engine operating parameter is engine speed.
 5. The method asclaimed in claim 2, wherein the second engine operating parameter is oilpressure.
 6. The method as claimed in claim 2 wherein the second engineoperating parameter is battery voltage.
 7. The method as claimed inclaim 2 wherein the second engine operating parameter is fuel pressure.8. A method for restarting a generator set where the generator set iscomprised of a generator driven by an engine, a controller in signaltransmitting and receiving relation with the engine, means for sensing anon-running value of a first engine operating parameter, the controllerhaving a memory, the controller being in signal receiving relation withthe means for sensing a non-running value of the first engine operatingparameter, and means for restarting the engine, the restarting meansbeing in signal receiving relation with the controller; the methodcomprising the steps of:a) sensing the running value of a first engineoperating parameter while the engine is running; b) transmitting thesensed running value of the first engine operating parameter from thesensing means to the controller; c) in the controller, comparing therunning value of the first engine operating parameter to a predeterminedacceptable value for the first operating parameter; d) if the runningvalue is outside the predetermined acceptable range for the first engineoperating parameter, shutting down the engine by sending a signal fromthe controller to the engine; e) after shutting down the engine, pausingfor a period of time; and f) after pausing for a period of time in stepe), initiating a non-running pretrip routine comprising the steps of:sensing a non-running value for a second operating parameter for theengine; comparing the sensed non-running value of the second operatingparameter with a predetermined acceptable non-running value for thesecond operating parameter; aborting the non-running pretrip routine ifthe sensed non-running value for the second engine operating parameteris outside the predetermined acceptable value for the second operatingparameter; and g) initiating an engine restart routine if the sensednon-running value for the second engine operating parameter is withinthe predetermined acceptable value for the at second operatingparameter; the engine restart routine comprised of the step of sending astart signal from the controller to the engine to restart the engine. 9.The method as claimed in claim 8, further comprising the steps ofsensing of status of the second operating parameter after the engine hasbeen restarted to determine if the second operating parameter hasreturned to a value that is within the predetermined acceptableoperating range.
 10. The method as claimed in claim 8, wherein thesecond engine operating parameter is engine coolant temperature.
 11. Themethod as claimed in claim 8, wherein the second engine operatingparameter is engine speed.
 12. The method as claimed in claim 8, whereinthe second engine operating parameter is oil pressure.
 13. The method asclaimed in claim 8, wherein the second engine operating parameter isbattery voltage.
 14. The method as claimed in claim 8, wherein thesecond engine operating parameter is fuel pressure.
 15. A method forrestarting a generator set where the generator set is comprised of agenerator; a prime mover for driving the generator, sensor means forsensing the non-running value of at least one prime mover operatingparameter, and a means for stopping and restarting the prime mover; thegenerator set further comprising a controller in signal receiving andtransmitting relation with the at least one means for stopping andrestarting the prime mover, the controller including a controllermemory; the method comprising the following steps:a) executing a primemover pretrip diagnostic and startup routine comprised of the followingsteps:i) sensing a non-running value for at least one operatingparameter for the prime mover; ii) comparing the sensed non-runningvalue of the at least one operating parameter with a predeterminedacceptable non-running value for the at least one operating parameter;iii) aborting the pretrip routine if the sensed non-running value forthe at least one prime mover operating parameter is outside thepredetermined acceptable value for the at least one operating parameter;and iv) initiating the prime mover restart routine if the sensednon-running value for the at least one prime mover operating parameteris within the predetermined acceptable value for the at least oneoperating parameter.
 16. The method as claimed in claim 15 including theadditional step of transmitting the sensed non-running value of the atleast one prime mover operating parameter sensed in step (b) (i)to thecontroller.
 17. The method as claimed in claim 15 including theadditional step of displaying an alarm code if the sensed non-runningvalue for the at least one prime mover operating parameter is outsidethe predetermined acceptable value for the at least one operatingparameter.
 18. The method as claimed in claim 17 including theadditional step of storing the alarm code in the controller memory. 19.The method as claimed in claim 15 including the additional step ofdisplaying a PASS, FAIL or CHECK code on the controller.
 20. The methodas claimed in claim 2 including the further step of after restarting theengine, shutting the engine down permanently if during an engineoperating time period the number of instances where the second engineoperating parameter is outside the predetermined acceptable operatingrange exceeds a predetermined acceptable number of instances for theengine operating time period.
 21. The method as claimed in claim 20including the additional step of storing an engine shutdown signal inthe controller memory when the engine is shutdown, the signal includingthe time the shutdown occurred and the value of the second engineoperating parameter that caused the engine shutdown.
 22. The method asclaimed in claim 8 comprising the additional steps of: obtaining thevalue of the second engine operating parameter after the engine has beenrestarted; determining if the second engine parameter is operatingwithin a predetermined acceptable operating range; and shutting down theengine if the second engine operating parameter is not within thepredetermined acceptable operating range for the second engine operatingparameter.
 23. The method as claimed in claim 22 including the furtherstep of after restarting the engine, shutting the engine downpermanently if during an engine operating time period the number ofinstances where the second engine operating parameter is outside thepredetermined acceptable operating range exceeds a predeterminedacceptable number of instances for the engine operating time period. 24.The method as claimed in claim 23 including the additional step ofstoring an engine shutdown signal in the controller memory when theengine is shutdown, the signal including the time the shutdown occurredand the value of the second engine operating parameter that caused theengine shutdown.
 25. A method for stopping and restarting a generatorset where the generator set is comprised of a generator driven by aprime mover; prime mover sensor means for sensing running andnon-running values of prime mover operating parameters; means forrestarting the prime mover; a controller having a timer, and a memorywith a restart routine stored in the controller memory, the controllerbeing in signal receiving relation with the prime mover sensor means andsignal transmitting relation with the means for restarting the primemover; the method comprising the steps of:a) after the prime mover hasbeen shutdown, initiating the restart routine; the restart routinecomprising the steps of:i) comparing a non-running value of a firstprime mover operating parameter to a predetermined acceptable range forthe first prime mover operating parameter; ii) terminating the automaticrestart routine if the prime mover operating parameter is outside apredetermined acceptable range for the first prime mover operatingparameter; iii) if the non-running value of the first prime moveroperating parameter is within the predetermined acceptable range,sending a restart signal from the controller to the prime moverrestarting means thereby restarting the engine.
 26. The method asclaimed in claim 25 comprising the additional steps of: if the restartroutine is terminated, timing a pause interval; and after the pauseinterval has expired again initiating the prime mover restart routine.27. The method as claimed in claim 25 comprising the additional step ofmanually initiating the restart routine.
 28. The method as claimed inclaim 25 wherein the prime mover is a diesel engine, the methodcomprising the additional step of preheating the prime mover beforerestarting the engine.